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owners manual

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traxxas 1100 klein road plano texas 75074 phone 972-265-8000 toll-free 1-888-traxxas traxxas u.k p.o box 1128 winterbourne bristol bs36-2sh england phone 44-117-956-1002 internet www.traxxas.com e-mail support@traxxas.com entire contents ©2005 traxxas traxxas top fuel and ready-to-race are trademarks or registered trademarks of traxxas other brand names and marks are the property of their respective holders and are used only for purposes of identification no part of this manual may be reproduced or distributed in print or electronic media without the express written permission of traxxas note this manual covers trx 3.3 trx 2.5 and trx 2.5r racing engines some photos show the engine equipped with optional accessories such as the ez-start system headers and engine mounts that are not included in the engine package see the end panel of the engine box for exact contents based on your engine model number trx engines · 2

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before you proceed before you proceed carefully read and follow all instructions in this and any accompanying materials to prevent serious damage to your engine failure to follow these instructions will be considered abuse and/or neglect before running your trx racing engine look over this entire manual and examine it carefully if for some reason you decide a trx racing engine is not what you wanted do not continue any further your hobby dealer absolutely cannot accept a trx racing engine for return or exchange after it has been run warnings hints and cross-references throughout this manual you ll notice warnings and helpful hints identified by the icons below be sure to read them an important warning about personal safety or avoiding damage to your trx racing engine and related components special advice from traxxas to make things easier and more fun refers you to a page with a related topic support if you have any questions about your trx racing engine or its operation call the traxxas technical support line toll-free at 1-888-traxxas 1-888-872-9927 technical support is available monday through friday from 8:30am to 9:00pm central time technical assistance is also available at www.traxxas.com you may also e-mail customer support with your question at support@traxxas.com join thousands of traxxas r/c enthusiasts in our online community at www.traxxas.com traxxas offers a full-service on-site repair facility to handle any of your traxxas service needs maintenance and replacement parts may be purchased directly from traxxas or you can save shipping and handling costs by purchasing them from your local hobby dealer 4 5 6 7 safety precautions introduction trx racing engine illustrated terms to know 11 the fuel 14 the air filter 16 the carburetor 19 breaking-in your trx racing engine 24 tuning the trx racing engine for best performance 29 troubleshooting your trx racing engine 33 maintaining and storing your trx racing engine 36 rebuilding the trx racing engine 42 index trx engines · 3

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safety precautions safety precautions all instructions and precautions outlined in this manual should be strictly followed to ensure safe operation of your trx racing engine trx racing engines are not intended for use by children under 16 years of age without the supervision of a responsible and knowledgeable adult trx engines · 4 all of us at traxxas want you to safely enjoy your new trx racing engine operate your trx racing engine sensibly and with care and it will be exciting safe and fun for you and those around you failure to operate your trx racing engine in a safe and responsible manner may result in property damage and serious injury the precautions outlined in this manual should be strictly followed to help ensure safe operation you alone must see that the instructions are followed and the precautions are adhered to · model engine fuel is dangerous and highly poisonous always follow all directions and precautions printed on the fuel container model engine fuel is poisonous to humans and animals drinking the fuel can cause blindness and death handle with care and respect · model engine fuel especially when in a fuel dispensing bottle may look like a cool drink to a child keep all fuel out of the reach of children at all times do not place fuel containers on the ground where children can get to them while you are driving · model engine fuel is flammable never allow smoking sparks heat or flame in the presence of fuel or fuel vapors · the engine and exhaust system may become extremely hot during use be careful not to touch the parts especially when refueling or stopping the engine · prolonged exposure to the engine exhaust can be harmful avoid breathing the engine exhaust always run your trx racing engine outdoors in a well-ventilated area never run the engine indoors · do not operate your model at night or anytime your line of sight to the model may be obstructed or impaired in any way · never operate your model in crowds of people or busy pedestrian areas trx racing engines make models very fast and could cause injury to those unaware of its presence · because your model is controlled by radio it is subject to radio interference from many sources beyond your control since radio interference can cause momentary loss of control always allow a safety margin in all directions around your model to prevent collisions · the engine can be loud if the noise makes you uncomfortable wear ear protection be considerate of your neighbors by not running your model early in the morning or late in the evening · most importantly use good common sense at all times.

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introduction introduction trx racing engines are the next generation of trx nitro power the larger displacement and advanced porting generate class-leading horsepower while still maintaining the trx racing engine characteristics of broad linear power delivery and ease of tuning focused engineering and rigorous testing have yielded unprecedented power and uncompromising performance that turns ready-to-run into ready-to-race® trx racing engines take a total-system approach each part of the engine from the air filter to the exhaust tip is carefully engineered to work in harmony with other engine components each part complements the next to extract maximum power trx racing engines are designed to be tolerant of variations in tuning and running through a wide range of variable atmospheric conditions such as changes in temperature humidity and altitude trx racing engines are manufactured to exacting tolerances and requires a speciallydesigned break-in procedure to accomplish the final precision fitting of the internal engine components it is very important that you follow the new break-in procedure as closely as possible to achieve the best performance and longest life from your trx racing engine old style break-in procedures such as simply running the engine with a very rich fuel mixture for the first 4 tanks of fuel will not achieve the best results follow the steps in this manual to successfully break in your trx racing engine a routine maintenance schedule is also required to keep your trx racing engine in top running condition cleaning the air filter after each hour of running is particularly important also it is extremely important to perform after-run maintenance on the engine to prevent corrosion of the internal engine components see page 34 traxxas strongly discourages changing or modifying any part of your trx racing engine old tech tips and tricks that may have boosted the power of other engines could seriously diminish the performance of your trx racing engine there s more advanced thinking development and testing in the stock parts of your trx racing engine than in many aftermarket manufacturer s so-called performance parts trx racing engines are already some of the most powerful engines in their class and simply will not benefit from average low-tech aftermarket bolt on performance items trx engines · 5

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trx racing engine illustrated trx racing engine illustrated head protector air filter base glow plug powertunetm head cylinder head pull starter if equipped air filter housing high-speed needle fuel intake air intake carburetor flywheel crankshaft clutch bell trx engines · 6 not included idle speed screw optional backplate if equipped low-speed needle crankcase throttle arm trx 3.3 engine shown other trx racing engines are very similar

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terms to know makes of engines follow the traxxas directions for break-in exactly carb abbreviation for carburetor carburetor the carburetor atomizes mixes .15 .15 or 15 refers to the displacement of the fuel with the air so that the engine can the engine the trx 2.5 racing engine is .15 burn it there are two types of carburetors cubic inches or 2.5 cubic centimeters cc the slide carbs and barrel carbs trx engines use name trx 2.5 is derived from the cc the superior slide carburetor design measurement clean-out cleaning-out is a condition that .20 .20 or 20 refers to the size of the engine occurs when the engine is accelerating and the trx 3.3 is .20 cubic inches or 3.3 cubic the fuel mixture becomes sufficiently lean to centimeters cc the name trx 3.3 is allow the engine to continue into its upper derived from the cc measurement rpm power band it is usually characterized by abc abbreviation for aluminum brass and a noticeable decrease in blue exhaust smoke chrome refers to engine construction that and a dramatic increase in engine speed consists of an aluminum piston that slides in combustion chamber the combustion a chrome-plated brass sleeve trx engines chamber is machined into the bottom of the use abc construction cylinder head this is where the glow plug air filter the air filter sits atop the carburetor ignites the fuel the shape of the combustion and prevents harmful dust and dirt from chamber is designed to promote more entering the engine dirt ingestion is the efficient burning of the fuel number one cause of premature engine connecting rod the connecting rod failure so the engine should never be run transfers the piston motion to the without the air filter in place crankshaft trx racing engines use a bdc bottom dead center the bottom-most knife-edged connecting rod the position of the engine piston stroke aerodynamic sharpened edges allow it break-in break-in is the procedure for running to slice through the pressurized air/fuel a brand new engine according to specific mixture inside the crankcase instructions this correctly prepares the crankcase the engine s body that contains engine for normal running the break-in all of the running mechanical components procedure can be different for different terms to know you ll find these nitro r/c engine terms throughout this section of the manual trx engines · 7

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terms to know crankshaft the main shaft of the engine that holds the reciprocating assembly cooling fins the cooling fins are milled into the cylinder head and crankcase and cause heat to be drawn away from the engine heat is removed when it dissipates into the air passing across the cooling fins it is important to keep the fins clean of dirt and debris for maximum cooling efficiency cylinder head head the finned aluminum part on top of the engine that is responsible for dissipating most of the engine s heat the combustion chamber is machined into the bottom of the head dyno abbreviation for dynamometer a precise piece of testing equipment that accurately measures engine power and torque output over the engine s entire rpm range ez-start traxxas on-board electric starting system the system consists of a hand held starter control unit and an on-board gearbox with an electric motor to spin the engine filter foam the oiled foam element inside the air filter housing the filter foam in the engine must be thoroughly cleaned and re-oiled after every hour of run time fit usually refers to the fit of the piston and sleeve if the fit is tight the piston will feel very tight at top of the sleeve top dead center trx engines · 8 and the engine will have good sealing and compression if the fit is loose compression will be low and both the piston and sleeve should be replaced flame-out occurs when the engine stops running at high rpm usually the fault of an excessively lean fuel mixture or glow plug failure fuel 10 20 33 the engine must have model engine fuel to run traxxas top fueltm is recommended fuel is sold in quarts and gallons from hobby dealers the 10 20 and 33 labeling refers to the percentage of nitromethane contained in the fuel see nitro percentage definition fuel mixture the ratio of fuel to air as determined by the needle settings of the carburetor fuel tubing fuel line the thick silicone tubing that carries fuel from the fuel tank to the carburetor glow plug the glow plug is located in the cylinder head at the top of the combustion chamber it contains an element that glows red hot when voltage is applied when the engine is being started the heat from the glow plug ignites the fuel mixture and starts the combustion process glow plug driver this tool clips onto the glow plug and supplies the required voltage to

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terms to know light the glow plug element it is also called an igniter ez-start equipped engines do not require this separate tool header the aluminum tube that connects the exhaust system to the engine exhaust port the length and diameter of the header must be carefully selected to extract the most power from the engine high-speed needle hsn adjusts the carburetors fuel/air mixture at high throttle openings idle speed the speed rpm the engine runs at when the transmitter s throttle trigger is at neutral idle speed screw iss located on the carburetor body this screw adjusts the idle rpm of the engine lean a running condition where the engine is not getting enough fuel for the available air symptoms include engine overheating or the engine runs for a short time and then stalls particularly at high speed this is a dangerous condition that should be corrected immediately or it can ruin your engine leaning the mixture turning either the high-speed and/or low-speed needles clockwise to decrease the amount of fuel the engine receives low-speed needle lsn needle valve that controls the fuel mixture at low throttle openings needle valve valve consisting of a tapered needle that closes against a corresponding seat to regulate fuel flow nitro abbreviation for nitromethane a component of model engine fuel that improves fuel combustion and power output nitro also refers to a class of r/c powered by model engines instead of electric nitro content the amount of nitromethane used in the fuel usually measured as a percentage of the total fuel volume traxxas engines are optimized to use 10-20 nitro 33 nitro may be used for racing nitromethane nitromethane is a component in the fuel that increases power from the combustion process up to a point engines are generally optimized to use a range of nitro content for the best power o-ring rubber o shaped ring used as a sealing gasket pipe abbreviation for the tuned exhaust pipe on a nitro engine see tuned pipe piston the piston is the internal engine part that is attached to the upper end of the connecting rod and moves up and down in trx engines · 9

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terms to know trx engines · 10 the cylinder sleeve the precise fit between the piston and the sleeve creates a seal that allows the engine to have the required compression for combustion port ports are openings in the sleeve that allow atomized fuel to enter the combustion chamber and burned exhaust gases to exit the shape and location of the ports are a large factor in controlling the engine timing and power output priming manually causing fuel to move from the fuel tank up to the carburetor this is sometimes necessary after the engine has been sitting for a long period of time and all of the fuel has drained back to the tank on a traxxas model this is done by holding your finger over the exhaust tip for one or two seconds while the engine is starting punch a term that refers to how quickly the model responds to throttle input or how quickly it accelerates rich a running condition where the engine is getting too much fuel for the available air it is better to run an engine slightly rich to increase engine life excessively rich mixtures cause the engine to have sluggish performance with exaggerated blue smoke and unburned fuel coming from the exhaust rpm abbreviation for revolutions per minute how many times the engine crankshaft spins in a minute sleeve internal engine part that contains the piston the precise fit between the sleeve and the piston creates a seal that allows engine to have the required compression for combustion the sleeve in a trx engine is made of brass and is then hard-chrome plated slide carburetor the throttle on a slide carburetor closes and opens by sliding a barrel in and out of the carburetor body this type of carburetor is preferred for performance use because it provides a less restrictive straight-through air path than the barrel carburetor design stall when the engine stops running usually due to an incorrect fuel mixture setting or running out of fuel tdc top dead center the top-most position of the engine piston stroke tuned pipe the tuned exhaust pipe usually consists of a specially-shaped metal or composite chamber with baffles that is designed to enhance the power output of the engine wear-in fitment process that occurs during engine break-in where internal engine parts develop an even more precise matched fit through actual use under controlled circumstances wot abbreviation for wide-open throttle.

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the fuel the fuel use the right fuel it s imperative that you use the correct fuel in your trx racing engine for maximum performance and engine life traxxas top fueltm should be used to ensure correct engine lubrication performance and ease of tuning traxxas top fuel has been proven in thousands of engines so you can count on it every day for great performance · top fuel is the only fuel which is 100 certified for use in traxxas engines · traxxas top fuel is made with just the right balance of the highest grade natural and synthetic lubricants to allow excellent throttle response and the best top-end performance without sacrificing long-term durability · all of the components in the fuel are carefully selected from the best materials available and then custom blended to match the metallurgy and temperature characteristics of traxxas engines you may use 10 20 or 33 nitro-content fuel try to use the same percentage all the time avoid switching back and forth between fuels we recommend that if you break in your engine on 20 fuel that you stick with that percentage if you do move to a higher or lower percentage make sure you readjust your fuel mixture to compensate danger model engine fuel is poisonous to humans and animals drinking the fuel can cause blindness and death handle with care and respect keep it out of reach of small children at all times while driving do not leave your fuel dispensing bottle on the ground where a child could have access to it follow fuel label warnings choosing a nitro percentage a commonly asked question is what is the difference between 10 20 and 33 fuels increasing the nitro in the fuel is almost like adding extra oxygen to the combustion process it burns more efficiently improves combustion and delivers more power when increased nitro is used more of the other fuel components are then required inside the combustion chamber to maintain the perfect air/fuel ratio therefore overall fuel mixtures trx engines · 11

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the fuel need to be richened slightly on the high speed needle about 3/4 of a turn counterclockwise when changing from 20 to 33 about 1/2 of a turn counterclockwise when changing from 10 to 20 this allows greater fuel flow through the engine and promotes cooler running even at the maximum lean settings if 33 improves power then it seems that the highest nitro content available beyond 33 should always be used in the engine in reality there are practical limitations engines are designed to run best within a range of nitro percentages how the engine is ported the size of the combustion chamber and other factors determine how much nitro can be efficiently used in the engine trx racing engines respond exceptionally well to a maximum of 33 nitro returning cooler temps more power and a smoother throttle response for those who want to run higher nitro 33 top fuel is the optimum nitro percentage for trx racing engines increasing the nitro beyond 33 can introduce the need for engine modifications ports head shimming etc to avoid starting and tuning difficulties there are limits to how much nitro an engine can effectively use to make more power lower nitro percentages have their own advantages nitro is an expensive component in the fuel so 10 nitro blend is more economical for the sport user 10 also provides greater latitude with the needle settings for easier tuning when using traxxas top fuel using higher nitro percentages does not cause the engine to wear out faster 33 top fuel contains the same quality lubrication package as 10 and 20 top fuel some non-traxxas high-percentage nitro racing fuels do sacrifice some lubrication in attempts to increase performance we urge you to not take chances with your engine investment and use top fuel for consistent performance and long engine life what about other fuels can other brands of fuel be used besides top fuel there are other fuels that can provide satisfactory performance however there could be long-term costs in the form of decreased engine performance loss of tuning ease and shorter engine life only use fuels that contain both castor and synthetic oil trx engines · 12

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the fuel everyone has an opinion or a claim to make about fuel the engineering team at traxxas has spent years developing trx racing engines no one knows more about the specific fuel requirements of traxxas engines than traxxas engineers we strongly urge you not to take chances with your engine investment and use the traxxas fuel made for trx racing engines handling the fuel · follow all directions and warnings on the fuel can · keep the fuel tightly capped at all times some components in the fuel can evaporate very quickly and upset the balance of the fuel · do not store unused fuel in the fuel dispenser immediately return fresh unused fuel back into the fuel can · do not mix old and new fuel never mix different fuel brands together · store the fuel in a cool dry location away from any source of heat ignition or combustion · read and follow the safety precautions on page 4 in this manual trx engines · 13

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the air filter the air filter clean your air filter after every hour of runtime to avoid engine damage even if the filter looks clean the trx racing engine air filter is specifically designed to deliver maximum performance while protecting your engine from dust and dirt use only the supplied filter you will not improve engine performance by switching to an aftermarket filter and you may risk engine damage due to poor filtration the trx racing engine air filter assembly consists of 3 pieces 1 a rubber filter base 2 a plastic housing consisting of a permanently assembled mesh cap and body 3 an oiled foam element you must clean the filter after every hour of run time even if the filter looks clean this includes the break-in time clean your air filter after break-in dust which is often too fine to see and dirt constantly move through the filter anytime the engine is running even if you can t see dirt on the filter it is present inside the foam after any amount of run time if you exceed the recommended cleaning intervals your engine will be damaged engine damage or wear due to dirt ingestion is easy to detect and one of the top causes of premature engine failure air filter cleaning instructions 1 remove the air filter from the carburetor bore by pulling the entire filter assembly firmly to the side to release it do not pull straight up 2 disassemble the filter pull the rubber air filter neck out of the filter body with the base removed the foam element is visible in the bottom of the filter body pull out the foam element 3 clean the filter parts by thoroughly washing all three pieces of the filter assembly in hot soapy water dishwashing detergent works well repeat twice if you use compressed air to dry your air filter assembly wear safety glasses and avoid directing compressed air toward your skin if foam filter oil is not available clean 30 or 40 weight motor oil can be substituted but is not preferred never run the engine without a properly oiled filter trx engines · 14

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the air filter 4 thoroughly dry the parts with a clean towel or compressed air remember to wear your safety glasses when working with compressed air 5 oil the foam element with foam filter oil use the supplied traxxas filter oil part 5263 or a high-quality special-purpose foam filter oil like what is used for off-road motorcycle and atv engines.this type of filter oil is available at motorcycle pro shops apply 30 drops of the traxxas filter oil evenly to the top bottom and sides of the filter element 30 total drops divided among the 3 surfaces squeeze the filter element repeatedly to help spread the oil throughout the filter element should be evenly colored by the oil even color indicates that the oil is distributed evenly do not squeeze out excess oil note do not use the air filter oil for anything other than the air filter it is not meant to be a lubricant 6 reassemble the filter and install it on the engine making sure the rubber filter neck fits securely on the carburetor with no gaps or air leaks trx engines · 15

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